The invention relates to a method for the production of structural ceramics and/or functional ceramics consisting of silicon-containing carbide ceramics, in particular, silicon carbide ceramics.
In addition, the invention relates to a component consisting of structural ceramics and/or functional ceramics consisting of silicon-containing carbide ceramics, in particular, silicon carbide ceramics.
DE 199 47 731 discloses a method for the production of structural ceramics and/or functional ceramics consisting of silicon carbide ceramics, with which a porous precursor body is produced from a cellulose-containing material, the porous precursor body is converted into an open-celled or open-pored carbon body by means of pyrolysis and the open-pored carbon body is converted into silicon-containing carbide ceramics, in particular, silicon carbide ceramics as a result of infiltration of silicon-containing materials, in particular, silicon or silicon alloys.
In addition, DE 199 47 731 A1 also discloses a component of this type.
In the case of the known method for the production of such components consisting of structural ceramics and/or functional ceramics, wood ingredients in the form of coarse chips or veneered wood layers of different thicknesses are used. A porous precursor body does result due to pressing but distinct density gradients are present in this body on account of the pressing techniques.
In addition, an anisotropy is to be noted due to the fact that the precursor body is compacted to a greater extent in the edge areas than in inner areas.
The anisotropy is extremely noticeable, in particular, in the case of the layer construction of individual wood veneer layers.
Altogether, the precursor body has a relatively inhomogeneous construction in all spatial directions which, again, results in a uniform discharge of the gases from the precursor body being prevented during the pyrolysis.
In addition, a considerable deformation cannot be avoided during the pyrolysis.
Altogether, the ceramic structure obtained has a coarse texture and, apart from silicon carbide, has locally occurring areas with high enrichments of residual silicon and residual carbon. The cause of this is likewise to be seen in the use of the coarse wood chips and the veneer layers and the intergranular cavity formation connected therewith.
Altogether, the structural ceramics and/or functional ceramics produced by means of the known method as well as the components obtainable therefrom can be manufactured with properties which can be reproduced only to a small degree.
The object underlying the invention is, therefore, to improve a method of the type described at the outset in such a manner that the structural ceramics and/or functional ceramics as well as the components produced therefrom can be produced with properties which are as reproducible as possible.